Tube spacer tool

ABSTRACT

A tool assembly for making spacing projections on a heat exchanger tube is inserted into the tube. A piston with wedges on the sides is moved longitudinally under hydraulic pressure. The wedges force balls outward through openings in the tool assembly and against the inside surface of the tube to form the projections.

v United States Patent 1151 3,640,1 15

Duncan et a1. Feb. 8, 1972 1 TUBE SPACER TOOL 2,183,921 12/1939 Reuter et a1. 72/75 [72] Inventors: Richard Duncan; George H salmno 2,657,733 11/1953 Champlon ..72/75 both of Richand wash 2,319,216 5/1943 Dewald .....72/393 3,555,831 1/1971 Pogonowslu .....29/523 [73] Assignee: The United States of America as =.3,068,55Q 12/1962 Liebreich ..72/75 represented by the United States-Atomic 568,574 9/1896 V Hoyer ..72/75 Energy Commission, I 1 'O v f FOREIGN PATENTS OR APPLICATIONS [22] Filed: Dec. 19, 1969 1 236,473 4/1959 Australia ..72/75 pp 886,632 215,182 6/1941 Switzerland ..72/75 521 u.s.c1 ..72/393,72/75,72/399, -Prinidry Eiminercharlesw- Lanham 29 234 Assistant ExaminerMichael .1. Keenan 511 mu. ..B21d 4l/02,B21b eya Anderson [58] Field ofSearch ..72/75,393, 399, 400, 370; v 1

113/118 R, 118 B; 29/444, 455, 507, 523, 506, 234, [571 ABSTRACT I B tool assemblyfor making spacing projections on a heat 1 exchanger tube is inserted into the tube. A piston with wedges [56] Reierences Cited on the sides is moved longitudinally under hydraulic pressure. UNITED STATES PATENTS The wedges force balls outward through openings in the tool 1 assembly and against the inside surface of the tube to form the 465,957 12/1891 Willmott ..72 370 projection, 3,349,600 10/1967 Bijovet "72/393 1 3,103,068 9/1963 Hinz et a] 29/523 2Claims,5Drawing Figures .5 /9 -l'-' 1' /7 as, if ,ng /i 27, z 4 i 3 I an. r HYDRfll/LIC con W04 I 5y5TM L W" TUBE SPACER TOOL CONTRACTUAL ORIGIN OF THE INVENTION The invention described herein was made in the course. of, or under, a contract with the United States Atomic Energy Commission.

BACKGROUND OF THE INVENTION A form of heat exchanger in wide use incorporates a structure in which a small tube is positioned within a larger tube. To properly position the small tube spacers are provided which position and support the small tube within the large tube. The small tube is normally centrally located within the large tube but may be offset if desired.

The spacers formerly used have been in the form of ribs or feet welded or otherwise fastened to the small tube. In a typical heat exchanger large numbers of these tubes are used as the rate of heat exchange and efficiency increases as the surface area of the tubes increases. Each tube must be supported at many locations, depending upon its length, and each point of support usually requires at least three spacers. Thus in the manufacture of heat exchanger tubes of this type large numbers of small parts must be attached to the tubes and the smaller tube inserted into the larger tube. With close tolerances required, insertion of a long tube may be very difficult. Since heating is usually involved in the attachment of the spacers a heat treating process may be required after the spacers have been attached. Thus it would be expensive to fabricate large numbers of these tubes.

It is therefore an object of this invention to provide an improved tool for forming spacer projections on the outside of the tube.

Another object of this invention is to provide a tool for developing large numbers of spacer projections on a tube without requiring the attachment of a separate structure for each spacer or group of spacers.

Another object of this invention is to provide a tool which can form the spacer projections on the outside of a small tube inserted in a large tube.

SUMMARY OF THE INVENTION In practicing this invention a tool assembly is provided for forming spacer projections in the walls of a tube. The tool assembly has a cylindrical housing with an outside diameter of a size so that the tool enters the tube with a close fit. The housing has at least one opening in the side thereof and includes an interior cylinder portion adapted to receive hydraulic fluid under pressure. A piston is positioned within the cylinder portion and at least one longitudinal portion is formed on the outside surface of the piston and positioned opposite the opening in the housing. Hydraulic fluid under pressure forces the piston to move longitudinally thereby moving the wedge across the opening in the housing. A ball is positioned on the wedge and extends through the opening against the inside of the tube. The longitudinal movement of the wedge acts to force the ball outward against the inside of the tube to develop a projection on the tube. Normally three wedges would be positioned on the piston to form three equally spaced projections. The number of projections is not limited to three and the shape is not limited to a spherical shape but may be any shape required.

DESCRIPTION OF THE DRAWINGS The invention is illustrated in the drawings in which:

FIG. 1 is a cross-sectional view of the entire tool assembly and hydraulic system;

FIG. 2 is a cross-sectional view of a portion of the structure of FIG. 1 showing the action of the wedge;

FIGS. 3 and 4 are cross-sectional views of FIG. 2 showing the spacing and action of the wedges and balls, and

FIG. 5 is a view of the ball retaining cage.

DETAILED DESCRIPTION OF THE INVENTION can be formed withthe small tube II in its final position inside tube 10 thus simplifying the final assembly of the heat exchanger tubes.

The interior of housing 13 has an open portion 15 which forms a cylinder. A series of holes 21 between the outside of housing 13 and the cylinder 15 are located around the circumference of the housing 13. While the drawings show three holes 21 located in the same plane and equally spaced, the invention is not limited to this number and the holes can be located in separate planes and irregularly spaced. A plug 14 having an opening 18 closes the cylinder 15. Hydraulic tubing 16 and 20 connects an hydraulic control system 17 to cylinder 15. Meter 19 indicates the pressure of the hydraulic fluid applied to the tool assembly.

A piston 23 is located within cylinder 15 and is free to move longitudinally within the cylinder. A seal 22 is positioned at the hydraulic fluid end of the piston to prevent the hydraulic fluid from leaking past piston 23.

An expansion control plunger 25 having a spindle 26 projecting from one end is positioned within housing 13. A guide and expansion control piece 28 closes one end of housing and has an opening which receives spindle 26. A spring 29 encircles spindle 26 and is compressed between expansion control plunger 25 and the guide and expansion control piece 28. An expansion control screw 35 limits the travel of spindle 26 and expansion control plunger 25. By this means the travel of piston 23 is limited. A setscrew 37 locks expansion control screw 35 in a desired position.

In operation hydraulic fluid under pressure enters cylinder 15 through opening 18 and forces seal 22 and piston 23 to the right. As piston 23 moves to the right expansion and control plunger 25 moves to the right compressing spring 29. Piston 23 continues to move to the right until spindle 26 strikes expansion control screw 35. When the hydraulic fluid pressure drops spring 29 forces expansion and control plunger 25 and piston 23 to the left.

Piston 23 includes a plurality of longitudinal wedges 3l spaced around piston 23 and positioned opposite holes 21. A ball 32 is positioned on each wedge and extends through the hole 21 adjacent the wedge. A retainer 34, extending around cylinder 23.keeps each ball 32 in its properhole 21. An expanded view of retainer 34 is shown in FIG. 5.

In operation when the hydraulic pressure applied to the tool is a minimum the piston is moved to the left position (FIG. I) by spring 29. In this position the balls 32 are retracted (FIGS. 1 and 2) and the tool is positioned as desired within tube 11. Hydraulic pressure is then applied to cylinder 15 forcing piston 23 to the right until spindle 26 strikes expansion control screw 35. This movement causes wedges 31 to force balls 32 up into tube 11 to develop projections on the outside of tube 11 (FIGS. 2 and 4).

By controlling the amount of movement with expansion control screw 35, the height of the projection is controlled. After the projections have been formed, the hydraulic pressure is released, the piston 23 and wedges 31 move to the left and balls 32 are retracted. The tool is then free to be moved to another desired position.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A tool assembly for constructing heat exchanger tubing, including in combination, a cylindrical first tube and a cylindrical second tube having an outside diameter substantially smaller than the inside diameter of said first tube and positioned within said first tube, a cylindrical housing of a size to enter said second tube with a close tit and having a plurality of openings in the side thereof, said housing further having an interior cylinder portion adapted to receive hydraulic fluid under pressure, piston means positioned within said interior cylinder portion and including a plurality of longitudinal wedge portions on the outside surface thereof with each of said wedge portions positioned opposite a separate one of said openings, a plurality of balls each positioned on a separate one of said wedges with a portion of each of said balls extending through one of said openings, said piston having an initial position, said piston means being responsive to said hydraulic fluid under pressure to move from said initial position longitudinally along said interior cylinder portion whereby each said wedges moves relative to said openings, said motion of said wedges acting to force each of said balls through said openings and against the walls of said second tube to develop projections thereon, spring means positioned within said cylindrical housing and mechanically connected to said piston, said longitudinal movement of said piston from said initial position acting to compress said spring means, said compressed spring means acting to develop a bias force to return said piston to said initial position upon the release of said hydraulic fluid pressure, an expansion control spindle mechanically connected to said piston and moving longitudinally therewith, stop means connected to said cylindrical housing and positioned so that said longitudinal movement of said piston means causes said expansion control means to strike and stop means thereby limiting said longitudinal movement to a predetermined amount and the height of each of said projection to a particular value, said stop means being adjustable to adjust the height of said projections to space said second tube within said first tube in a desired relationship.

2. The tool assembly of claim 1 wherein, said cylindrical housing has three openings in the same plane and equally spaced around said side of said cylindrical housing, and said piston means has three longitudinal wedges. 

1. A tool assembly for constructing heat exchanger tubing, including in combination, a cylindrical first tube and a cylindrical second tube having an outside diameter substantially smaller than the inside diameter of said first tube and positioned within said first tube, a cylindrical housing of a size to enter said second tube with a close fit and having a plurality of openings in the side thereof, said housing further having an interior cylinder portion adapted to receive hydraulic fluid under pressure, piston means positioned within said interior cylinder portion and including a plurality of longitudinal wedge portions on the outside surface thereof with each of said wedge portions positioned opposite a separate one of said openings, a plurality of balls each positioned on a separate one of said wedges with a portion of each of said balls extending through one of said openings, said piston having an initial position, said piston means being responsive to said hydraulic fluid under pressure to move from said initial position longitudinally along said interior cylinder portion whereby each said wedges moves relative to said openings, said motion of said wedges acting to force each of said balls through said openings and against the walls of said second tube to develop projections thereon, spring means positioned within said cylindrical housing and mechanically connected to said piston, said longitudinal movement of said piston from said initial position acting to compress said spring means, said compressed spring means acting to develop a bias force to return said piston to said initial position upon the release of said hydraulic fluid pressure, an expansion control spindle mechanically connected to said piston and moving longitudinally therewith, stop means connected to said cylindrical housing and positioned so that said longitudinal movement of said piston means causes said expansion control means to strike and stop means thereby limiting said longitudinal movement to a predetermined amount and the height of each of said projection to a particular value, said stop means being adjustable to adjust the height of said projections to space said second tube within said first tube in a desired relationship.
 2. The tool assembly of claim 1 wherein, said cylindrical housing has three openings in the same plane and equally spaced around said side of said cylindrical housing, and said piston means has three longitudinal wedges. 